We will continue our study of the responses of interneurons in the intermediate nucleus of decerebrate cats. The validity of our present classification scheme which identifies interneurons according to their dominant muscle afferent input (i.e., Ia, II, Ib or high threshold stretch receptors) will be tested by increasing the numbers of neurons isolated. We will examine the pattern of convergence of afferents from different muscles, and also assess whether different types of muscle afferents converge upon the same interneuron. Finally, the efferent projections of identified interneurons will be studied using spike-triggered averages of intracellular membrane potential recorded from regional motoneurons.